With prevalence of renewable (reproducible) power supplies of which outputs are difficult to predict, it is demanded to improve precision of supply and demand adjustment capability. The supply and demand adjustment capability is a capability to change electricity demand or electricity supply in response to an instruction so as to cancel imbalance between supply and demand. Specifically, the supply and demand adjustment capability may be a capability to change an amount of charge and discharge at a power storage apparatus, or to change a load variation of a controllable load.
For example, in order to prevent a fluctuation in outputs of renewable power supplies from adversely affecting an upper system, a method of stabilizing fluctuations in power flows at a connection point (such as a substation or a microgrid, that is under control of power distributing operators), through which a certain area is linked to the upper system, is known. Specifically, in the method, an amount of supply and demand adjustment is changed by using supply-and-demand adjustment apparatuses installed in the area so as to cancel the output fluctuation.
Herein, the supply-and-demand adjustment apparatus is an apparatus that may change electricity demand and electricity supply. The supply-and-demand adjustment apparatus includes, for example, a power storage apparatus such as a lithium-ion battery, a lead storage battery, and a NAS battery (registered trademark), a controllable load, a small-sized power generator, and the like.
The supply-and-demand adjustment amount is an amount of electric power to be consumed or supplied by the supply-and-demand adjustment apparatus in response to an instruction.
PTL 1 describes a method to set a priority order for respective power generators, based on control characteristics and control states thereof, and sequentially to allocate a required amount of power control in descending the order of priority. Specifically, the method disclosed in PTL 1 is expected to realize highly precise responses by sequentially allocating the supply-and-demand adjustment amount from the supply-and-demand adjustment apparatus with smaller delay.
PTL 2 describes a supply and demand control technique for microgrids, to conduct supply and demand adjustment by reflecting respective characteristics of an internal combustion power generating facility and a power storage apparatus.